What is Vthr?
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Hi all, I've been reading some of the procedural items in the F28 manual to improve my practices (and try to break some probably bad habits) in advance of the V2 release. The manual references Vthr a number of times, but a search within the PDF doesn't turn up a definition as far as I can find, and I've also been unable to find one via google. Drawing from context within the manual, I'm guessing it's another abbreviation for Vt, as it seems to be the target speed across the threshold, but if so, how do I know what to target for that speed? Too many 737 flights have led me to just use Vref + 5 / "Vapp." On the other hand, referencing the tutorial flight leads me to think it's just another notation for Vref ("At 100 ft, gradually reduce speed to cross the threshold at 122 knots.") - 122 was the Vref shown on the chart for a flaps 42 landing.
Thanks in Advance!
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I believe it's something similar to the Boeing. I’ve set aside something from the FCTM for analysis. Hope it helps.
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Thanks. What this diagram shows is also detailed in a way in the manual, as well. And it looks like Vthr is just a different notation for Vt, but I'm still not sure how to arrive at the actual speed. I guess I'll just treat it as Vref, which has always worked out okay for me lol (unless I hear otherwise).
And I'll look at the diagram a little more after I've had my coffee!
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Vthr is the threshold speed (i.e. the speed at which you should aim to cross the threshold). The Vthr speed for each of the landing flap settings is displayed on the speed card in the cockpit.
For a normal approach, once the aircraft is configured for landing and stabilised on the glide path, the approach should be flown at Vthr + 10 knots. At approximately 100ft, the speed brake is then selected out and that should begin bleeding off speed, reaching Vthr at touchdown.
Hope that helps.
Mark - Just Flight
